Monitoring watches for conditions you defined in advance and alerts when they occur. Observability is the ability to understand a system from the outside by asking new questions of its telemetry. Security teams need both: monitoring for known bad events, observability for investigating the unknown.
Definitions
The OpenTelemetry observability primer says observability lets you understand a system from the outside, and that it helps you troubleshoot unknown unknowns and answer the question of why something is happening. It defines telemetry as data emitted from a system and its behavior, and describes signals as the kinds of telemetry that instrumented code emits: traces, metrics and logs. That page does not define monitoring, so the next paragraph is our working definition.
Monitoring, in everyday practice, is the set of checks and alerts you write for conditions you already know about: a service is down, error rate is above a threshold, a login failed ten times.
Side by side
| Monitoring | Observability | |
|---|---|---|
| Starts from | A known condition | A question you did not plan for |
| Output | Alert, dashboard | Answer from exploring data |
| Strength | Fast, cheap, clear | Flexible, good for new failures |
| Weakness | Blind to what you did not anticipate | Needs rich, well structured data and skill |
| Security example | Alert on repeated failed logins | Trace one suspicious session across five services |
How this plays out in security
A monitoring rule catches the attack you expected. An investigation after a surprise needs data that was recorded before you knew you would need it: request identifiers, user and tenant IDs, timestamps in a shared format, which service handled what. If that data is missing, no tool can reconstruct it.
That is why the groundwork matters more than the label. See structured log fields every log line needs and logs, metrics, traces: which to set up first.
Steps to build both
- Write down the ten conditions you must be told about. These become monitoring alerts.
- Write down five questions you would ask in an incident. Check that your telemetry could answer each one.
- Add a request or trace ID that flows through every service.
- Keep security events out of sampling. See head or tail sampling.
- Remove secrets from telemetry before you store it. See redact at the source or in the pipeline.
- Practise: pick a past incident and see whether your current data would have let you reconstruct it.
Common mix-ups
Buying more dashboards does not create observability. Having traces does not replace alerts. Collecting everything is not the aim either, since more data means more sensitive data to protect and pay for.
Quick check
Are logs, metrics and traces the same as observability?
They are the signals observability depends on. Observability is the ability to use them to answer new questions.
Do I need observability if I have good alerts?
Alerts cover what you predicted. Observability helps with what you did not, such as a novel attack path.
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Sources
Last reviewed: 19 October 2026.
